This math video focuses on functions. It explains how to tell if a relation is a function given a set of ordered pairs or a data table. In addition, it explains how to use the vertical line test to determine if a graph or curve is a function based on if it touches the line at two or more points. Finally, this video discusses the domain and range of functions briefly. Functions - Free Formula Sheet: Domain and Range - Free Formula Sheet: Functions - Video Lessons: Final Exam and Test Prep Videos: